We switched from a low-end shared hosting account with BlueHost to a high-end dedicated server with a great company in Tampa called Hivelocity. They also have data centers in LA, NYC, and Atlanta.
The price difference more than makes up for the speed and customer service that they provide. We are very happy to have our own server with an SSD, lots of RAM, on a super-fast network, plus now there is no throttling like what a shared server gives you.
It seems like they have fanatical customer service just like Rackspace, but their prices are much better – they even have an Server Outlet with heavily discounted prices.